Fuel injector



July 14, 1953 J, D. TUKER 2,645,182

FUEL INJECTOR Filed April 16, 1948 2 SheQtS -Sheat l -INVENTOR J .D.Tucker BY MM ATTORNEYS July 14, 1953 J. D. TUCKER FUEL INJECTOR 2Sheets-Sheet 2 Filed April 16, 1948 7 u -Y////// J// 07in v INVENTORJLD, Tucker mi v-wzai/ ATTORNEYS Patented July 14, 1953 (UNITED...STATES PATENT OFFICE V l I 2,645,182 I I '1' I p INJECTOR I Jesse D.-Tucker, Lodi, Calif., assignor' of onefourth to Boine W. Fuller, .Lodi,Calif., onefourth to Murray E. Milholland, and onefourth toJesse D.Tucker, Jr., both of Sacra-.

mento, ,Calif'.

Application April 16, 1948, Serial No. 21,519 I Claims. (01. 103-37)This invention is directed to, and it is an object to provide; animproved fuel'injector for diesel engines. I

Another object'of the invention is to provide a' fuel injector whichincludes a" plurality of plunger-type fuel metering and distributingunits in novel combination with a central fuel feed chamber whichdelivers to said units.

A further object'oftheinvention isto provide a fuel injector," as in'thepreceding paragraph, which incorporates a receiving chamber and a bleedback arrangementfor the recovery of the high pressure fuel which tendsto work back along the plungers'j suchfrecovered fuel being returnedto'th'e supply tank; 4

An additional object of the invention is to provide a'iuel injectorwhich incorporates a novel mechanism for selectively controlling thepressure of the fuel as red from the feed pump to the injector, wherebyto regulate engine speed, and allowof efficient idling withoutstalling.-

A further object is to provide means, operated automatically by fuelpressure change, to alter the effective stroke 'of the injectorplungersso that the amount-of fuel metered'and fed to-the engine witheach stroke will be increased as the engine speeds up.

A further object of the invention is to pro-.-

vide a practical and reliable fuel injector and one which will beexceedingly effective for the purpose for which it is 'designed. Theseobjects are accomplished by means of such structure and relativearrangement of-parts as will fully appear by a perusal of the followingspecification and claims. I In the drawings: Fig. 1 is a sectionalelevation of the improved fuel injector shown with the plungersin theposition of greatest stroke efiiciency. I

Fig. 2 is a half sectional elevation of the injector with the plungersin the position of minimum stroke efficiency. Fig. 3 is an end view ofthe main bodyof the fuel injector, taken from the outlet end; I

Fig. 4 is an end view of the stroke-position ad-l justing cam disc. I

Fig. 5 is an end view of the plunger actuating cam disc and showingitsspecific driving connec-v tion with the drive shaft. y i Referringnow more. particularly to the characters of reference on the drawings,the improved injector comprises a main body I of generally cylindrical,elongated form; Such body including,

on one side thereof, a mount 2 for attachmentof the device to a suitablesupport. e

. At one end the body is fitted with a threadedon-cage 3, which includesan end'bearingd in which a driven shaft 5 is 'journaled. The drivenshaft 5 projects into the cage 3 and is there'fitted with a rotary cam 6having suitable thrust bearings associated therewith.

The n ain body I is formed with a plurality of circumferentially spaced,longitudinal bores 1 which extend parallel t'othe body axis and'areinitially open to both ends thereof.

P1ugs8 are threaded into the bores 1 at the end of the body opposite therotary cam 6, each of said plugs including an axial passage 9 in which acheck valve 'ID'is' interposed; said check valve being'spring closedinwardly. The plugs 8 include fittings H by means of whichthecorresponding feedpipes .12 are connected to the injector; said feedpipes leading to corresponding ones of the engine jets (not shown)Directly inwardly of the plugs 8 the bores l are each of somewhatreduced diameter fora certain distance, and this reduced-diameterportion of each boreis fittedwith a'cylinder forming sleeve "l3, whichincludes internal rings, as

shown.

Spring-retracted; cam-advanced plungers *l 4 rotary cam 6; the rollersbeing carried in slid- ,able guide heads l6. g Helical compressionsprings ll surround the plungers l4 between the sleeves l3 and guideheads [6, and said springs normally act to retract theplunge'rs l4,maintaining the rollers l5 always in contact with the rotary cam 6. Eachcylinder-forming sleeve l3, together with the .corresponding plunger l4,and the related working parts, form' what may be termed a fuel meteringand distributing unit. 2 1

The body. isformed, adjacent the sleeves l3,

with, a central fuelfeed chamber 1 8, from which radial, .,fuel-deliverypassages l9 lead into the cylinders, formedby the sleeves I 3, and inwhich cylindersthe plungers l lwork.

Fuel under pressure is delivered into the ber l8 asfollowsz.

The forward-part by an end plug .20, screwed into the body cenw; trallyat its forwardend; saidplug including a passage 2|, to which thejfuelsupply .pipe 22 is connected by a fitting 23. Fuel under pressure feedsfrom pipe, 22. through the fitting, 23. and

plug 20 into thechamber l8, and thence cows through passages l9 into thecylinder forming, u sleeves l3, when said cylinders are open byretraction of the corresponding plungers.

In retracted positionof the plungers Q H,-the;

of the chamber!!! is defined,

3 passages I9 are uncovered so that fuel, under pressure, may deliverinto the cylinders formed by said sleeves I3. Of course this fuel entryinto the cylinders, and operation of each plunger I4 for fuel injection,occurs successively by reason of the cam operation. In other words, eachtime a plunger I4 retracts, a charge of fuel enters the correspondingsleeve I3, and with advance of said plungers the corresponding passageI9 is closed off and the fuel is then forcefully delivered through therelated check valve I into the communicating delivery pipe I2 leading toan,

engine jet.

The fuel supply pipe 22 is fed from a relatively high pressure fuel pump(not shown), and the I following bypass and control valve mechanism isemployed, to the end that the pressure of the fuel as delivered to theinjector may be selectively regulated by the operator and an effectiveidling action of the engine automatically obtained when the latter isrunning free. 7 I

Such mechanism comprises a lateral 24 connected to pipe 22 andterminating in a cylindrical projection 25 within a body 26 and forminga valve seat for a needle valve 21 opening away from pipe 22. The needlevalve, which is in effect a check valve, has a stem 27a slidablyprojec'ting from the body and connected to a barrel 28, serving as aretainer for a compression spring-29 which urges the stem to a valveclosing position.

A piston 30' in the barrel 28 engages the end of thes'pring 29 oppositethe stem 210,; said piston having an axial rod 3| projecting outwardlytherefrom through a fixed member 32.

An adjustment collar C on the rod 3| bears against the member 32 tolimit outward movement of the piston 30 under the influence of thecompression spring 29.

The collar C serves as an initial adjustment proportionately greatervolume is injected by the device into the engine.

It will thus be seen that the load of spring 29 on stem 21a and valve 21controls the extent of by-passing of fuel from lateral 24 (and pipe 22)through an outlet 33 from, body 26, and thus regulates the fuel pressurein supply pipe 22 and in the fuel feed chamber I8.

Surrounding the cylindrical valve seat projection -25 is a cup 34adjustablymountedon stem 21a. within the body and below the needlevalve; the bor of said cup from its base up having a slight clearancefit about projection .25 for a short distance when the needle valve isclosed, and then flaring to its outer end as at 35. Cup 34 is thusapiston on the stem, the flat bottom of the cup providing a moreeffective fuel-contacting area for the pressure of the fuel to open thevalve, than that provided by the needle valve itself.

Thus, when high pressure fuel opens the needle valve, such fuel, beforeit can escape through outlet 33, acts on the larger cup surface to lowerthe same. This in turn lowers the needle valve further, causing arelatively large'flow of fuel to enter the 'cup and lower the same. Thiscup movement lowers the flare 35 so that a relatively large escapepassage from the cup into the body (and to outlet 33) is thus provided.The pressure of the fuel in the line 22 is thus lowered almostimmediately, which acts on the injector to reduce the amount of fuel fedthereby to the engine and provides for efficient idling of the same byreason of the mechanism hereafter described. Since the fuel pump whichcreates the pressure is driven by the engine, and such pumpgeneratedpressure bears a direct relation to engine speed, it will be seen that avery sensitive control arrangement is provided.

In addition to the above described structure, I have provided amechanism operated by changes in fuel pressure in pipe 22 as controlledby manipulation of rod 3|, to alter the setting of the plungers I4relative to intake passages I9 so that each plunger stroke, while ofunchanging length, will have an increasingly effective pumping actionwith increase in pressure in pipe 22.

This mechanism in the main is interposed be-' tween the fixed bearing 4and the cam disc 6, which is slidable but non-turnable on the shaft, andis constructed as follows:

Slidably fitted in cage 3 for axial movement back of disc 6 is anotherdisc 36, there being thrust balls 31 between the discs.

The back or outer face of disc 36 is provided with arcuate cam grooves38 arranged about a circle concentric with theshaft 5 and increasingevenly in depth from one end. Balls 39 engage the different grooves 38in the same relationship to each other, and ride on bearing 4. The ballsare mounted in a keeper disc 40 turnable on the shaft 5 so that withrotation of said disc, the balls are moved about the shaft and areshifted along grooves 39.

It will thus be seen that if the disc 40 is rotated in one direction orthe other through an are not greater than the length of any groove 38,disc 36 and cam 6 will be advanced as balls 39 ride up the grooves 38,and-will be retracted (by reason of the pressure of springs II thereon)as the balls 39 move down into the grooves.

As a result, the fully advanced position of plungers I4 may be shiftedfrom a point adjacent plugs 8 and a correspondingly long distance beyondpassages I9, as shown in Fig. 1, to one just a short distance beyondintake passages I9,-

as indicated in Fig. 2. With the former position of the plungers, arelatively great amount of fuel will be discharged into pipes I 2 ascompared with the amount of fuel fed into said pipes with the latterposition of the plungers as will be evident.

The disc 40 is thus rotated, with changes of fuel pressure in pipe 22 bymeans of a hydraulic cylinder unit 42, the piston rod 43 of which isconnected to disc 40 outside cage 3, as shown in Fig. 3. The feed pipe44 to said cylinder is connected to pipe 22 so that pressure in saidpipe will advance the piston rod in a direction to advance disc 36,while a spring 45 is applied to rod 43 to retract the same when thepressure in the cylinder is reduced and thus rotate disc 40 in theopposite direction or so as to cause retraction of disc 36 and cam disc6. Thus, when the pressure in pipe 22 is high, as determined by pressureagainst valve 21, the plungers I4 act through a stroke of greaterfuel-pumping efficiency, as when the engine is under load, than when thepressure in said pipe is low, as when ed by balls 46 caged and riding inholes 41 in said disc and engaged in longitudinal grooves 48 formed inpins 49 secured to and slidably projecting through disc 6 parallel tothe shaft 5 from a plate 50 secured thereon.

In the described fuel injector, where the fuel is under very highpressure in the cylinders formed by the sleeves l3, some fuel may workback along said plungers 14. The following arrangement is provided forthe recovery of such fuel, and to the end that it will not be lost:

Rearwardly of the central fuel feed chamber 18, the body I is formedwith another and separate central chamber 51 which may be termed thefuel return chamber; there being a return passage 52 from the chamber 51to the fuel tank (not shown).

Adjacent the forward end of the fuel return chamber 51, the body isformed with radial bleed-back passages '53 leading into communi,- cationwith the cylinders formed by the sleeves l3. The position of thebleed-back passages53 axially of the device is such that when theplungers 14 are in fully retracted position they do not uncover saidpassages. With reciprocation of the plungers 14 fuel which may tend towork back along the plungers gains access to the bleed-back passages 53and flows into the feed return chamber 5|, whence it is delivered by thereturn passage 52 to the fuel tank. With this arrangement an economy offuel is accomplished.

The described fuel injector, while being relatively simple in itsstructure, is nevertheless quite rugged, and provides a practical andeffective mechanism for the injection of high pressure diesel type fuelsto en ines.

From the foregoing description it will be readily seen that there hasbeen produced such a device as substantially fulfills the objects of theinvention, as set forth herein.

While this specification sets forth in detail the present and preferredconstruction of the device, still in practice such deviations from suchdetail may be resorted to as do not form a departure from the spirit ofthe invention, as defined by the appended claims. 7

Having thus described the invention, the following is claimed as new anduseful, and upon which Letters Patent is desired:

1. A fuel injector comprising a body having a cylinder therein, thecylinder having a head, a fuel outlet passage from said head of thecylinder, a fuel inlet passage leading to the cylinder a distance fromsaid head, a fuel pressure line leading to said inlet passage, a plungerslidable in the cylinder, means to reciprocate the plunger through astroke of constant length from a point ahead of the inlet passageway toa point beyond the same, such latter means including a driven shaft, arotary cam mounted in driving relation on the shaft and shiftableaxially thereof, one end of the plunger riding said cam, and applied tothe cam means to shift the cam axially along the shaft in one directionwhereby to alter the range of reciprocation of the plunger relative tosaid inlet passage; said last named means com--,

prising a non-rotatable disc movable axially on the shaft and on whichthe cam is rotatably mounted, the face of the disc opposite the cambeing providedwith an arcuate cam groove of increasing depth from oneend and disposed in an arc concentric with the shaft, a fixed-levelsupport for the disc turnable about the shaft, a disc-supporting elementin the support ridable in the cam groove, and means to turn the support.

2. An injector as in claim 1 in which the last named means includes ahydraulic ram connected in operating relation to the support, and meansto'supply hydraulic pressure to the ram.

3. An injector as in claim 2 in which the means to supply fluid to theram comprises a feed pipe leading from said pressure line to saidhydraulic ram and effective to lead fluid under pressure from theconduit to the ram, and a spring acting on said support against thepressure in the ram.

4. A fuel injector comprising a cylinder having a head end, a fueloutlet passage from said head end, a fuel intake passage leading to thecylinder a certain distance from said head end thereof, a fuel pressureline leading to the inlet passage, a

plunger slidable in the cylinder, means to reciprocate the plungerthrough a stroke of constant length from apoint ahead of the intakepassage to a point beyond the same and including a rotary member mountedfor movement axially of the plunger and whose rotation reciprocates theplunger, another fuel pressure line connected to the first namedpressure line, and means between the member and said other pressure lineand actuated by pressure therein to move said member axially.

5. A fuel injector comprising a cylinder having a head end, a fueloutlet passage from said head end, a fuel intake passage leading to thecylinder a certain distance from said head end thereof, a'fuelpressureline leading to the inlet passage, a plunger slidable in the cylinder,means to reciprocate the plunger through a stroke of constant lengthfrom a point ahead of the intake passage to a point beyond the same andincluding a rotary member mounted for movement axially of the plungerand whose rotation reciprocates the plunger, mechanism'to move themember axially in one direction, and hydraulic pressure means to actuatethe mechanism, and a fuel pressure line connected to the firstnamedpressure line and to the last named means to actuate the latter.

. JESSE D. TUCKER.

References Cited in the file of this patent UNITED STATES PATENTS WidmerDec. 12, 1950 v

